1. Field of the Invention
The present invention relates to a container for printing material that is attached to a printing device and holds a printing material therein, as well as to a technique of detecting a status of the printing material held in such a container.
2. Description of the Related Art
Diverse containers of printing materials used for printing devices have been proposed; for example, ink cartridges for ink jet printers and toner cartridges for laser printers and photocopiers. There is a requirement to detect the status of the printing material held in such a container for appropriate management of the printing material. One known technique measures the status of ink remaining in the container (for example, the residual quantity of ink or the temperature, the viscosity, or the pressure of ink) and uses the measurement result to manage the ink level in the cartridge or regulate the size of ink droplets. Various detection elements are applicable for such measurement. A technique of using a piezoelectric element for a sensor that measures a residual quantity of ink is one example (Patent Laid-Open Gazette 2001-147146). The piezoelectric element is distorted under application of a voltage. The known technique utilizes such distortion to generate a vibration. The technique places a piezoelectric element to face a cavity and observes a variation in frequency or a resonance due to a vibration induced by a distortion of the piezoelectric element to detect the quantity of ink remaining in the cartridge. The printing device establishes communication with the cartridge to obtain the remaining quantity of ink detected by the sensor. A contact-type communication system that brings the cartridge in electrical contact with the printing device or a non-contact type communication system that utilizes a radio wave is applicable for communication between the cartridge and the printing device.
The magnitude of the induced vibration depends upon the degree of distortion of the piezoelectric element. A low given voltage and a small degree of distortion may thus cause an insufficient vibration, which results in malfunction of the sensor. The cartridge communicating with the printing device by the non-contact communication system does not receive a direct supply of electric power from the printing device. The electric power for driving the sensor is thus to be produced by electromagnetic induction of the received radio wave. The prior art cartridge can, however, generate only a small electric power through the electromagnetic induction and has difficulties in actuation of the sensor that requires application of a relatively high voltage. This problem of insufficient power supply arises even in a container equipped with a battery as part of the power source, when the electric power consumed by the sensor exceeds the electric power supplied from the battery.
This problem is not restricted to the ink cartridge for holding ink therein, but is also found in various cartridges and containers for holding printing materials, for example, a toner cartridge.